Steve Saunders Goldwing Forums banner
Status
Not open for further replies.
1 - 20 of 106 Posts

·
Pwhoever
Joined
·
3,377 Posts
Discussion Starter · #1 ·
imported post

I have noticed this topic coming up quite frequently. A search would reveal a lot of different threads and I actually started one a while back myself but I wanted to add a more recent one to help others with this....

This method is works only if there is a schrader/air valve in the top fork bolt.

I have started doing the fork oil change as annual maintenance. There is a method to do it where you can do it very simply and get the level right everytime.

The confusing thing is that level and volume keeps getting interchanged but in essence, they are basically one and the same. If you can figure out the level (distance from the top of the fork tube), then you will already know the volume (amount of cc's) that need to be added. These forks need the level to be equal in both forks even though different amounts of oil go in each. This is because there are different components in the left as opposed to the right and this changes the amounts of oil each one holds. (Although this doesn't apply to Interstate models, they use equal volume in both forks.) But the one constant is that the level will end up being identical. This is because of the level of air needs to be the same in both sides. Even though Progressive says to add no air which technically is correct, there is still air in the forks and this plays into the damping. When the forks are compressed, as in driving down the street, going over bumps, cornering, etc... This amount of air will also play into the mechanics of how the fork works. Because of this, the amount of air needs to be identical in each or there will be different amounts of pressures at work on the left and right forks which could cause a serious handling issue.

An example of volume and level.... Let say you need 1-1/2 cup of milk. You pull out a glass measuring cup and carefully measure it out using the markings. Now you pour that into another glass cup that you plan on using all the time that has no markings. So after you pour the milk into this separate glass, you make a mark at the level where the milk is. The next time you need 1-1/2 cups of milk, you will no longer need to measure it, you just pour the milk into this glass up to the mark and if it goes over, you pour out the excess. If it's too low, just add some more. This will work for everytime you need 1-1/2 cups of milk. Technically you are still measuring out 1-1/2 cups each time but you already know in advance that putting the milk to the mark will get you the amount you need. So no need to think about it.

Satan on this board took the time to do some extensive measuring of the 88-94 and 95-00 forks and simplified the levels. Most times the service manual only gives the levels and volume with springs out and the forks fully collapsed. That is the hard way. Changing the fork oil with the forks fully extended with the springs still in wasn't known and most folks took their best guess at what it should be. But this information is what was wanted. He was in the middle of a fork rebuild so was able to take both measurements and this is what he came up with:

Oil fill with forks collapsed and springs out (from the shop manuals):
239mm / 9.4" for 88-94
194mm / 7.6" for 95-up

Of course that kinda sucks if you've got springs in your bike and you're refilling through the air valve...
... so measuring from the TOP OF THE FORK NUT (schrader valve removed) looks more like this --

Oil fill with forks fully extended and springs installed (measured from the top-plane of the fork nut with the air valve removed):
400mm / 15.75" for 88-94 (Progressive springs installed tight end down)
406mm / ~16" for 88-94 (Progressive springs installed loose end down)
408mm / ~16.1" for 88-94 (OEM springs installed)
* 355mm / ~14" for '95+ (Progressive springs installed tight end down)
* 361mm / ~14.2" for '95+ (Progressive springs installed loose end down)
* 363mm / ~14.3" for '95+ (OEM springs installed)


With that said, the method is foolproof and actually pretty easy way to do it quickly and get the same results each time. All you need is a way to jack up the front of the bike while on center stand so the forks are fully extended, a bottle of your favorite fork oil, a length of aquarium air hose and a syringe like this one:



(Satan used a length IIRC of 3/8" copper tubing straightened and a fender washer to set his level. I use the aquarium tubing because I already had it.) Cut 2 lengths of aquarium tubing. The first one make long enough to reach the bottom of the bottle of fork oil and attach this one first. Second, based on above mentioned levels, figure out which measurement fits your particular application and cut the aquarium tubing to the proper length. If the tubing is too tight, you can use a larger phillips head screwdriver to expand the tubing. It usually has quite a bit of flex before it tears. Obviously drain the old fluid during which removing the schrader/air valve makes it drain quicker. I will sometimes usea nozzleon my compressor set at lowand stick it in the top holeand help blow some of the remaining fluid out. Don't use too high a pressure or fluid will spray everywhere out the drain hole and make a mess. After it finishes draining, put the drain plug back in andstart pulling fork fluid from the bottle through the first aquarium tubing filling the syringe. Now take the end of the aquarium tubing and start putting it through the hole left by the removed schrader valve. Squeeze out the new fluid. Do this about 5 times in each side (based on using a 60cc syringe). Lower the jack and take the bike off the center stand. While sitting on the bike, grab a handful of the front brake and vigorously get the forks pumping up and down maybe 10-15 times. This will allow the fork oil to work down into the lower part of the forks. Now get it back on the center stand and jack up the front end again. Now attach the longer tube and fill up the syringe one more time about halfway. Same thing as above, if it gets caught up, twist the syringe and tubing so all the tubing goes down in. Squirt that in but this time after the syringe is empty, while the tube is still inside, start drawing the plunger out. If fluid starts filling the syringe, you know that it was overfilled and you are now drawing out the excess. empty the excess, put the tube back in and repeat until no more fluid enters the syringe. If nothing comes out then you know you have to add more fluid to that side. Repeat on other side. Pull the tube back out, put the schrader valve back in and you are done. You now have the proper amount of fluid in there. The beauty of this is that it doesn't matter if a little fluid was left behind from draining, the level will never change. If some fluid was left, using the level method, you end up putting in less new fluid automatically anyway. If you were to completely ensure that you drained all the fluid now in the forks, the volume otherwise known as cc's would match the cc's called for in the factory manual.

As a side note, you will now have the proper amount of air in there for Progressive springs. If you check it, even though there is air, it will measure 0 psi. Now when you lower the jacked up front end and take the bike off the center stand, there will be small measurable psi but it actually never changed. The reason this is important is that if you let the air out while the forks are slightly compressed, (normal riding position) it will limit the forks ability to extend all the way if they need to such as rebounding over bumps because you will end up in a negative psi condition with the forks fully extended. Kind of like a vacuum chamber....



Edited to correct the wrong info on the 95+. Thanks again Stan...
 

·
Premium Member
Joined
·
325 Posts
imported post

Bit of clarification for some please . . . .


"Oil fill with forks collapsed and springs out (from the shop manuals):
239mm / 9.4" for 88-94
194mm / 7.6" for 95-up"


Would this measurement be made down from the top of the tube, as in 9.4 inces of free space? Or does one need to make some sort of dip stick to measure oil depth of 9.4 inches?

:stumped:
 

·
Premium Member
Joined
·
1,250 Posts
imported post

pwoever,

Very good info.

I got my syringe from a vetrinarian just for the asking.

They throw them out every day.
 

·
Pwhoever
Joined
·
3,377 Posts
Discussion Starter · #6 ·
imported post

Luxo2r wrote:
Bit of clarification for some please . . . .


"Oil fill with forks collapsed and springs out (from the shop manuals):
239mm / 9.4" for 88-94
194mm / 7.6" for 95-up"


Would this measurement be made down from the top of the tube, as in 9.4 inces of free space? Or does one need to make some sort of dip stick to measure oil depth of 9.4 inches?

:stumped:
This info was the starting point that Satan used and is the info found in the manuals. This measurement is the free space/air inside the tube from the top level of fork oil to the top of the tube. But as mentioned, this measurement comes from the forks removed from the bike, the fork top bolt removed, the springs out and the fork tubes fully collapsed. This was only put in there as a point of reference. But based on this info, Satan was able to expand on this and came up with the information with spring in, extended forks. I just didn't feel like pulling the forks apart every time I wanted to change the fork oil.....
 

·
Premium Member
Joined
·
555 Posts
imported post

Just wondering if someone knows how many CC it takes in each fork (if you can do it that way) or do you have to do it by measuring it ?



Hickey
 

·
Pwhoever
Joined
·
3,377 Posts
Discussion Starter · #9 ·
imported post

You can do it by cc's but the problem is that unless you completely disassemble the forks, you cannot put the corrrect amount off cc's back in as the forks will not completely drain all the old fluid. What Satan did was to start with forks that had were completely empty and had just been rebuilt. He added the correct amount of fluid and gave the level that the forks would be at properly filled. Now there is absolutely no reason to ever measure the cc's of fork fluid. If you fill to that level, your forks are properly filled. Thats why this is so easy. Even if some fluid is left behind, by setting the proper level, you will just end up adding less fluid automatically. All you need to do is add fluid so the level is set. You will have the proper amount in each fork each and every time.

Another way to think about this is when changing your motor oil. Your engine has specific amounts on how much oil should be in there but how many take the time to measure it out? I don't know anyone who actually measures it exactly. The engine on the GL1500's should be 3.9 qts with a filter change.Unless you completely disassemble the engine, you will still have some old oil left behind.Most will pour almost 4 qts in and check the dipstick. You know that if the oil level reaches the line in the middle of the flat part on the base of the dipstick, you have the proper volume. If not you add a little more till it reaches. Did you add 3.9 qts exactly?Most likelynot because of oil left behind but is there now 3.9qts of oil in there. Probably and the level is where it needs to be so it can operate properly.

For informational purposes I know that for

88-94: Left Fork=325c's Right Fork=320cc's

95-00: Left Fork=372cc's Right Fork=377cc's (Aspencades and SE's)

I am not sure about the Interstate models.... I'm sure someone will come along with that answer.
 

·
Premium Member
Joined
·
1,299 Posts
imported post

I recently changed the fork fluid in my 1100 by draining the old fluid out, measuring how much came out, filling a measuring cup with the same amount. I used a mighty vac hooked to where the air valve is to pull vacuum on the tube.I hooked up a hose with a valve at the drain plug with another going into the new fluid, pumped up as much vacuum as I could, opened the valve and the new fluid was sucked into the tube. Replaced the drain plug with no fluid loss.Unless the seal is bad and you have lost fluid, you probably won't be able to pull vacuum on the tube. Plus the manual tells you how much fluid to use so I don't bother removing the cap and measuring the level. The reason I did it this way was to avoid wrestling getting the caps back on.It takes only a few minutes to do my way.,,
 

·
Just another ORF!
Joined
·
8,189 Posts
imported post

I'm in the midst of rebuilding my forks with new bushings/seals and Progressives etc.
Reading your/Satan's 'Fill Chart', I see a discrepancy.
My bike is a 92 Aspy and I have the 94 Honda Service manual and it states that you fill it to 7.6" below the top.
In the 'chart' you refer to, you have that level for 95 and up, and the 88-94 models at 9.4". I think someone has their measurements switched for the years?? :stumped:
Maybe it should read;

Oil fill with forks collapsed and springs out (from the shop manuals):

239mm / 9.4" for 95-up
194mm /
7.6" for 88-94


Dusty
 

·
Pwhoever
Joined
·
3,377 Posts
Discussion Starter · #12 ·
imported post

I have a 96 Factory Service Manual and a Haynes 88-00 manual. The 96 mentions the 194mm- 7.6" level. The Haynes also states for 95-Up 194mm-7.6" and for the 88-94 239mm-9.4".... So those are 2 sources giving he same information which matches the info from Satan. That is interesting that the 94 Service Manual mentions that.
 

·
Just another ORF!
Joined
·
8,189 Posts
imported post

Ya, that is strange. :stumped:

Okay .... I see where the problem lays. :readit:

The Honda service Manual I downloaded that I got the above measurement from, which is supposed to be for a 1994, actually isn't! :shock: :?

I just sat down for a bite for lunch and brought out my hard copy 94 manual and the figures you have stated are correct. My bad and more importantly, the down-loadable manual is probablyfor an other thanUS market94.:stumped:



Dusty .... learned something new today
 

·
Anti-Guru
Joined
·
2,711 Posts
imported post

:ssshh:(damn, and that was gonna be a secret :p ) :ssshh:



Suspension changes were in '95 (lower ride height, different damping fluids, etc) so the split years should be correct and the air-space reduction to 7.6 follows with the lighter springs and fluid.

Still, it'd be worth good investigation in a few years' and natinalityof manuals -- There could be US / export marketchanges as well as the front coils/multiple-coils/spacers have been quite different across that lot.

The data in the OP is from US market 1500/6 and 1500SE guides.















:action:
 

·
Premium Member
Joined
·
389 Posts
imported post

Not to ressurect (sp?) an old thread, but.........if this works only with forks with schrader valves, what about us Interstate guys who do not have schraders. Best procedure there?
 

·
Premium Member
Joined
·
98 Posts
imported post

I understand that the Interstate has the same fluid levels. How hard is it to remove the upper caps assuming that I have stock springs?
 

·
Premium Member
Joined
·
332 Posts
imported post

the only way to remove and replace the caps is to remove the fork tubes themselves and place them in a vice. It's the only way to push down on the caps to screw them in place, but it's not that hard to remove the fork tubes.
 
1 - 20 of 106 Posts
Status
Not open for further replies.
Top